Polymers stabilized with acyl hydrazones

ABSTRACT

NEW ACYL HYDRAZONES OF 2,2,6,6-TETRAMETHLYPIPERIDIN-4ONE ARE USED AS STABILIZERS FOR ORGANIC MATERIALS.

United States Patent 3,833,636 POLYMERS STABILIZED WITH ACYL HYDRAZONESBrian Holt, Royton, Donald Richard Randell, Stockport,

and James Jack, Bramhall, England, assignors to Ciba- Geigy Corporation,Ardsley, N.Y.

No Drawing. Original application Mar. 13, 1972, Ser. No. 234,333, nowPatent No. 3,745,163. Divided and this application Nov. 22, 1972, Ser.No. 308,910

Int. Cl. C08f 45/60; C08g 51/60 US. Cl. zoo-45.8 N 8 Claims ABSTRACT OFTHE DISCLOSURE New acyl hydrazones of 2,2,6,6-tetramethylpiperidin-4-one are used as stabilizers for organic materials.

R and R are the same or different and each is a straightorbranched-chain alkyl group having from 1 to 6 carbon atoms, and n is 0or 1;

as Well as the acid salts of these compounds.

Examples of substituents R and R are methyl, ethyl, n-propyl, isopropyl,sec. butyl, t-butyl, t-pentyl (1,1-dimethylpropyl) and t-hexyl(1,1-dimethylbutyl). Preferably one or both of R and R are t-butyl,although it is understood that it is unlikely that bulky groups such asthe t-butyl group will be on adjacent carbon atoms of the phenylresidue.

Examples of acyl hydrazones include:

2,2,6,6-tetramethylpiperidinyl-4-(3',5'di-t-buty1-4- hydroxybenzoyl)hydrazone 2,2,6,6-tetrarnethylpiperidinyl-4-(3',5' dimethyl-4'-hydroxybenzoyl hydrazone 2,2,6,G-tetramethylpiperidinyl-4- (3'-t-butyl-4'-hydroxy- 6'-methylbenzoyl hydrazone2,2,6,6-tetramethylpiperidinyl-4- 3 ,5'-di-t-butyl-4'- v2,2,6,6-tetramet.hylpiperidinyl-4- [ti- (3 ',5 '-di-sec-butyl-4-hydroxyphenyl) propionyl hydrazone2,2,6,6-tetramethylpiperidinyl-4-[,3-(3 ,5-diisopropyl-4'-hydroxyphenyl) ]propionyl hydrazone 2,2,6,G-tetramethylpiperidinyl-4-fl- 3-tbutyl-4'- hydroXy-5'-methylphenyl) ]propionyl hydrazone2,2,6,fi-tetrarnethylpiperidinyl-4- [,8- 3'-t-butyl-4-hydroxy-6-methylphenyl) propionyl hydrazone 3,833,636 Patented Sept. 3,1974 Ice 2,2,6,6-tetramethylpiperidinyll- [,B-methyl-fi- (3 ',5

di-t-butyl-4'-hydroxyphenyl) propionyl hydrazone2,2,6,6-tetramethylpiperidinylA- [B-methyl-B- (3 '-t-butyl-4-hydroxy-5'-methylphenyl) propionyl hydrazone 2,2,6,6-tetramethylpiperidinyl-4- fi-methyl-fi- 3 -t-butyl-4'-hydroxy-6-methylphenyl) propionyl hydrazone 2,2,6,6-tetramethylpiperidinyl-4- fi-methyl-fi- 3 ',5

diisopropyl-4'-hydroxyphenyl) ]propionyl hydrazone Examples of salts ofcompounds of formula I are those derived from inorganic acids such asphosphates, carbonates, sulphates, chlorides as well as those derivedfrom organic acids such as citrates, acetates, stearates, maleates,oxalates and benzoates.

Compounds of formula I in which A is -CH or CH CH and wherein n is 1 andcompounds of formula I where n is 0 are preferred, Most preferred arecom pounds having either the formula II or III:

wherein R has its previous significance, but wherein R is preferablyt-butyl and is attached in the position ortho to the hydroxyl group ormethyl which is attached in a position orthoor meta to the hydroxylgroup.

The present invention also provides a process in which a compound offormula I is prepared comprising reacting a compound having the formulaHO-Q-(ALr-(ENHNH:

wherein R R A and n have their previous significance, with a compoundhaving the formula:

The reaction is conveniently effected by heating the reactants together,preferably in a solvent which is inert under the reaction conditions,for instance an aliphatic alcohol such as ethanol, an aromatichydrocarbon such as toluene or a dialkyl ether such as diethyl ether.Advantageously, the reaction is conducted at the reflux temperature ofthe mixture using approximately equimolar proportions of each reactant.When the reaction is complete, the desired product may be purified byconventional techmques.

The present invention still further provides a composition comprising anorganic material and a minor proportion of a compound having the formulaI as hereinbefore defined.

The compounds of formula I provide protection to polymers containingthem, not merely against deterioration caused by visible or ultra-violetradiation but also against oxidative degradation caused by thermaleffects. Moreover, this stabilisation is achieved without affecting thecolour properties of the untreated polymer.

The stabilisers of the invention provide effective stabilisation forlowand high-density polyethylene and poly propylene in particular aswell as for polystyrene and also polymers of butene-l, pentene-l,3-methy1butene-1, hexene- 1, 4-methylpentene-l, 4-methylhexene-1 and4,4-dimethyl-pentene-l, as well as coand ter-polymers of olefines,particularly of ethylene or propylene.

Other organic material susceptible to degradation by the elfects oflight, and the properties of which are improved by the incorporationtherein of a compound of formula I, include natural and syntheticpolymeric materials, for instance, natural and synthetic rubbers such ashomoand co-polymers of acrylonitrile, butadiene and styrene andthermoplastic polyblends such as a terpolymer of acrylonitrile,butadiene and styrene.

Specific synthetic polymers, include polyvinyl chloride and vinylchloride co-polymers, polyvinyl acetate as well as condensation polymersderived from ether, ester (ex carboxylic, sulphonic or carbonic acids),amide or urethane groupings. These polymers can form the basis ofsurface coating media such as paints and lacquers having an oil orresin, for instance an alkyd or polyamide resin, base.

The amount of the compound of formula I which is incorporated into theorganic material in order to achieve maximal protection againstdegradation by light varies according to the properties of the organicmaterial treated and according to the severity of the light radiationand to the length of exposure. However, for most purposes it issufiicient to use an amount of the compound of formula I within therange of from 0.01% to 5% by weight, more preferably within the range offrom 0.1% to 2% by weight based on the weight of untreated organicmaterial.

Optionally, the composition of the invention may contain furtheradditives, especially those used in polyolefine formulations, such asantioxidants, further light stabilisers, metal complexants/deactivators,pigments, antislipping and anti-static agents, fillers, dyes and glassor other fibres.

The compounds of formula I may be incorporated into a polymeric materialby any of the known techniques for compounding additives with a polymer.For example, the compound of formula I and the polymer may be compoundedin an internal mixer. Alternatively, the compound of formula I may beadded as a solution or slurry in a suitable solvent or dispersant, forinstance, an inert organic solvent such as methanol, ethanol or acetoneto powdered polymer and the whole mixed intimately in a mixer, and thesolvent subsequently removed. As a further alternative the compound offormula I may be added to the polymer during the preparation of thelatter, for instance, at the latex stage of polymer production, toprovide pre-stabilised polymer material.

Examples of suitable antioxidants are those of the hindered phenol typesuch as 2,6-ditertiarylbutyl-p-cresol, 4,4his(2,6-ditertiarylbutyl-phenol), 4,4'-bis(2,6-diisopropylphenol),2,4,6-triisopropyl phenol, and 2,2'-thio-bis (4methyl-fi-tertiarylbutylphenol) tetrakisEmethylene-B '(3',5'dibutyl-4'-hydroxyphenyl)propionatelmethane; noctadecyl;8(4'-hydroxy-3,5'-t-butylphenyl)propionate, esters of thiodipropionicacid, for example dilauryl thiodipropionate; alkyl, aryl or alkarylphosphites such as triphenyl phosphite, trinonyl phosphite anddiphenyldecyl phosphite, and combinations of these antioxidants.

Further light stabilisers include those of the substituted benzotriazoleclass such as 2-(2-hydroxy-5'-methyl) phenylbenzotriazole, 2 (2-hydroxy3,5'-di-tbutyl)5- chlorophenylbenzotriazole; those of the hydroxybenzophenone type; hindered phenols such as 2,4-di-t-butylphenyl3,5-di-t-butyl-4-hydroxy benzoate and suitable metalcomplexants/deactivators include salicylidene-propylene diamine,5,5'-methylene-bis-benzotriazole and salts of salicylalaminoguanidine.

As with the compound of formula I, any further additive isadvantageously employed in a proportion within the range of from 0.01%to 5% by weight of untreated organic material.

In combination with an antioxidant suitable for use in inhibitingoxidative deterioration of polyolefines, for instance those of thehindered phenol type, the compounds of formula I provide extremelyeffective all round stabilising packages for polyolefines.

Some examples will now be given. Parts and percent ages shown thereinare by weight unless otherwise stated. Example 1 A mixture of 68.4 partsof ,8-(3,5-di-t-butyl-4-hydroxyphenyl)-propionic acid hydrazide and 31parts of triacetonamine in 150 parts of methanol was heated under refluxconditions for 12 hours. On removal of the methanol by distillationunder reduced pressure, a solid was left which was recrystallised frompetroleum ether to give 48 parts of2,2,6,6-tetramethyl-piperidinyl-4-[rt-(315'di-t-butyl-4'-hydroxyphenyl]propionyl hydrazone having melting point of127 C., and the following elemental analysis by weight:

A 0.15% weight/ volume solution of the product of Example 1 in acetonewas made up and 40 millilitres of this solution was added to 40 grams ofpowdered polypropylene which was substantially free from stabilisingadditives. A further 60 millilitres of acetone was then added to form aslurry which was hand mixed to ensure homogeneity. The solvent was thenremoved by evaporation in an oven maintained at C.

14 grams of the dried powder were weighed into a mould measuring 6 x 6 x0.015 inch. The mould and polishing plate were then heated in the pressunder constant pressure for 5 minutes.

A pressure of 20 tons per square inch was applied for one minute,cooling was commenced and pressure increased so that when thetemperature reached C. the

pressure was 80 tons per square inch. Cooling was continued until thetemperature of the mould reached 50 C. and the mould was released fromthe press.

The moulded sheet so obtained was exposed to light irradiation in afademeter device consisting of a circular bank of- 28 alternate sunlightand blacklight lamps. The sunlight lamps were 2 feet long 20-wattfluorescent lamps and were characterised by having a peak emission of3,100 angstrom units and blacklight lamps were. 2 feet long 40- wattultraviolet lamps and were characterised by having a peak emission of3,500 angstrom units. The samples were rotated concentrically about thebank of lamps so that the radiation therefrom was uniformly distributedover the moulded sheet.

The exposed sample was examined periodically and bent through and thetime at which it snapped due to embrittlement was noted.

An oven ageing test was also carried out on strips (6.0 x 1.0 inch) ofthe moulded sheet in an air circulating oven maintained at 150 C. Thetime taken for the test strip to fail by cracking on flexing the samplethrough 180 was noted. The results are set out in the following-Table I:

TAB LE I Time to embrittlement. in-

Heat- Light;- ageing ageing test test; Example Additive (homs) (hours)None 2 82 2-(2'-hydroxy-3',5-dt-t-butyl)-5- 2 250chlorophenylbenzotriazole. 2 2,2,6,o-tetramethylpiperidinylm 44 341ae-drt-but iphenoi-ni ro ionyi h ydrazone.

These results demonstrate the superior properties of a typicalcomposition according to this invention compared with a controlcomposition and also a composition stabilised with a known stabiliser.

Example 3 For CHHZBNIOI Found Required Percent:

Carbon 71. 96 71. 78 Hydrogen-.-. 9. 96 9.79 Nitrogen"--- 10. 28 10. 46

Example 4 A mixture of 7.30 parts of ,3-(3,5di-secbutyl-4-hydroxyphenyl)propionic acid hydrazide and 7.75 parts of triacetonamine in 120 partsof methanol was heated under reflux conditions for 12 hours. On removalof the methanol by distillation under reduced pressure, a solid was leftwhich was recrystallised from petroleum ether to yield 2.0 parts of2,2,6,6-tetramethylpiperidinyl-4[,8-(3',5'di-secbutyl- '-hydroxyphenyl)]propionyl hydrazoue as a white solid having a melting point of 142 to143 C. and the following elemental analysis by weight:

For CzsHaaNaOz Found Required Percent:

Carbon 72.86 72.68 Hydrogen..-- 10.03 10.09 Nitrogen-.-. 9. 87 9. 78

7 Example 5 A mixture of 12.50 parts of p-(3-t-butyl-4-hydroxy-5-methylphenyl) propionic acid hydrazide and 15.50 parts of triacetonaminein 150 parts of methanol was heated under reflux conditions for 12hours. On removal of the methanol by distillation under reducedpressure, a solid was left which was recrystallised from methyl alcoholto yield 10.50 parts of 2,2,6,6 tetramethylpiperidinyl-4-[B-(3'-t-butyl-4'-hydroxy-5-methylphenyl)] propionyl hydrazone as a whitesolid having a melting point of 187 to 188 C. and the followingelemental analysis by weight:

100 parts of crystal polystyrene pellets were dry blended with 0.25parts of the product of Example 1, and the dry blend was homogenised byextrusion. The stabilised pellets so obtained were injection moulded toform placques 2 mm. thick. These placques were exposed for varyingperiods in a Xenotest exposure unit, and any yellowing of the placqueswas measured by determining the yellowness factor by means of thefollowing equation:

wherein AT represents the transmission losses at wavelengths 420 mm. and680 mm. after exposure in the xenotest apparatus and T660) representsthe transmission value of an unexposed sample at a wavelength of 560 mm.

The results obtained, as well as the results relating to controlexperiments are recorded in Table II.

TABLE II Yellowness factor 100 1,500 2,000 2,500 3.000 Example Additivehrs. hrs. hrs. hrs. hrs.

None 7.8 15.7 235 31.4 37 6 ProduetolExamplel-.. Nil 1.1 50 6.7 10.1

Example 7 A mixture of 3.96 parts of 3,5-di-t-butyl-4-hydroxybenzoicacid hydrazide and 3.10 parts of triacetonamine was heated at reflux in60 parts of ethyl alcohol for 17 hours. Removal of the ethyl alcoholsolvent by distillation under produced pressure yielded a white solid,which 'was washed with ether to remove the excess triaoetonamine andcrystallised from ethyl alcohol to give 1.80 parts of 2,2,6,6tetramethylpiperidinyl 4 (3,5'-di-t-butyl-4'- hydroxybenzoyl) hydrazoue,having a melting point of 174 to 175 C.

The Infra-red and Nuclear magnetic resonance spectra were consistentwith this structure.

Example 8 CH: C

R1 HOQ(A)DENH-N- NH 2 43H: CH:

R and R are the same or diiferent and each is a straightorbranched-chain alkyl group having from 1 to 6 carbon atoms and n is 0 or1.

2. A composition of, claim 1 wherein said polymer is polyethylene,polypropylene or polystyrene. j

3. A composition of claim 2 wherein the stabilizer is employed in theconcentration of from 0.1 to 2.0% 1; weight of the polymer. 4. Acomposition of claim 3 wherein the stabilizer. is 2,2,6,6tetramethylpiperidinyl 4 (3',5-dimethyl-'4'- hydroxybenzoyl)-hydrazone.

5. A composition of claim 3 wherein the stabilizer is 2,2,6,6tetramethylpiperidinyl 4 (3', -di-t-butyl-4'- hydroxybenzoyl)-hydrazoue.

